This blade retainer kit is designed for use with string trimmers and edgers by many manufacturers. It comes with a metal retaining washer that is used with the blade, as well as the needed spool cutting heads. This kit also includes the nut needed to fasten the blade to the gearcase. It is used to install a blade onto the trimmer while adding stabilization through the nut. The parts in the blade retainer kit can become worn out during use and may need to be replaced.When the blade needs to be replaced or a part of the blade retainer kit is broken, removing the parts is required. Moving the blade involves turning the retaining bolt while the equipment is on a level surface. Next, undo the bolt holding the blade so it can be removed. The blade can be replaced at this time, as well as the parts from this blade retainer kit.This blade retainer kit is made for edgers and string trimmers manufactured by Yard-Man, Craftsman, Bolens, Ryobi, MTD, Troy-Bilt, and Yard Machines. It is a single retainer kit that comes as a genuine OEM replacement part sourced directly from the manufacturer.